Power loss with 351 in 86 GT please help!

5-oh stang

Founding Member
Apr 30, 2002
I had my 351W in my 68 mustang with a built AOD Edge 3200 Stall and 4.11 gears and that car with full interior (3300lbs) went 12.50's all day long at 110mph
here is the motor setup:
351W bored .030 over flat top pistons with 2 valve reliefs
AFR 185 CNC ported out the box heads 61cc chambers
Edelbrock performer RPM intake
Road Demon 725 cfm Vacuum secondary Carb
13* timing
Comp Cams Extreme energy Flat tappet 284/296 .541/.544
1.6 Roller rockers, the valve springs are whatever came on the AFR heads
Stock Duraspark Ignition
Holley mechanical fuel pump and all 3/8" fuel line

I put all this into a 86GT T-top with a T-5 Tranny and 373 gears, swaped over the durasprark ignition but instead of using a set of aftermarket headders i had to go with the factory headers off the 5.0 and make pipe to fit the offroad h-pipe. Seems like i lost alot of power somewhere. It will smoke the tires in 1st and about 6 feet in second but thats it! It should be melting the tires away with easy..... What could possibly be the problem, i open for any suggestions and sorry for being so loooonnng, just wanted to be detailed. Thanks alot!!!!!
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The shorties are choking the 351, i have one of those when my motor was in a 79 Fairmont and i can't even pass 5,600 revs, changed to 1¾ and the motor rev up to 6,200 w no other changes. you also said you have 13 of timing i assumed is initial, so what is the total timing?? also you have a cowl? do you use an Air Filter on top of your carb?

setup is very nice so i think the main reason is the shorties.. been there done that:nice:
i would have to agree that the factory shorties are where you are losing a lot of power. i have bbl 1 5/8 shorties and peeps say those choke my 351w. i have 18 degrees of intial timing in my 351w with 38 degrees over all. those things may help you. btw on the 86 car get your self a nice upper and lower control arm package for the rear. a set of strange 10 way adjustable struts and shocks wouldn't hurt either.
umm not running a air cleaner is a very bad idea man. cut a hole in your hood and get a scoop off a 83 mustang and bolt it on the hood. it looks sweet and then you won't have dirt getting in your engine and killing it.